The World Health Organization has endorsed a global strategy for the prevention and control of non-communicable diseases. Non-communicable diseases are to an extent preventable. Four of the most prominent non-communicable diseases - cardiovascular disease, diabetes, cancer, and chronic obstructive pulmonary disease - share common modifiable behavioural risk factors, namely tobacco use, unhealthy diet and physical inactivity.

These four diseases are among the leading causes of death, and among the leading causes of burden of disease. Cancer, diseases of the circulatory system and diseases of the respiratory system were the three leading classes of cause of death in Australia in 1998.

In Australia in 1996, the ten leading causes of burden of disease were Ischaemic heart disease, stroke, chronic obstructive pulmonary disease, depression, lung cancer, dementia, diabetes mellitus, colorectal cancer, asthma, and osteoarthritis (table 9.27). Burden of disease was measured using the disability-adjusted life year (DALY), which takes into account the impact of disability and other non-fatal health outcomes, as well as the impact of premature death. One DALY is equivalent to one lost year of 'healthy' life; and burden of disease is a measurement of the difference between current health status and the ideal of living into old age free of disease and disability.

9.27 LEADING 10 CAUSES OF BURDEN OF DISEASE AND INJURY, Percentage of Total Disability-adjusted Life Years - 1996

Considerable proportions of the overall burden of disease in Australia in 1996 were attributable to a number of major risk factors (table 9.28). The leading risk factor, tobacco smoking, was responsible for 10% of the total burden of disease, followed by physical inactivity (7%), high blood pressure (5%) and obesity (4%). Insufficient intake of fruits and vegetables (fewer than five servings per day) caused an estimated 3% of the total burden of disease and 11% of the cancer burden.

The following analysis of the three risk factors: tobacco smoking, physical inactivity and insufficient intake of fruits and vegetables, is based on data from the 1995 National Nutrition Survey. It should be noted that estimates on smoking and exercise may differ slightly from estimates generated from the 1995 National Health Survey which have been published elsewhere.

Smoking

In 1995, 21% of Australians aged 18 years and over regularly smoked, i.e. smoked more than one cigarette per day. Smoking rates were higher for males than for females, although smoking rates for both sexes followed similar patterns, generally falling with age.

However, the proportion of the population who had ever smoked regularly was quite different for men and women. This is largely an outcome of historical differences in smoking prevalence between the sexes. Around half of 25-34 year old males and females had smoked regularly at some stage in their lives. This reflects that in recent years the gap between smoking rates for men and women has been relatively small. However, this gap has been much greater historically, and so 72% of 65-74 year old males had ever smoked (the highest proportion of any age group), compared to only 39% of 65-74 year old women (graph 9.29). In older age groups, the proportion of men and women who had ever smoked decreases. This is likely to be a reflection of greater survival into older age groups by those who had never smoked, rather than historical patterns of smoking prevalence.

Physical inactivity

In 1995, 30% of Australians aged 15 years and over did no exercise for sport, recreation or fitness in a designated two-week period. The proportion of people who did no exercise increased slightly with age, from 26% of 18-24 year olds to 34% by 65-74, and 44% of people aged 75 years or more (graph 9.30). There was very little difference between males and females.

The intensity of exercise decreased more sharply with age, and there was a greater sex difference, with males more likely to engage in vigorous exercise than females. The duration of exercise, however, had a different age pattern, with the most exercise being undertaken by people aged 15-24 and 65-74, outside the prime working ages. Men, on average, spent more time exercising than women did.

Fruit and vegetable consumption

In 1995, about a quarter (26%) of Australians aged 18 years and over reported that they usually ate one serve or less of vegetables per day, and 50% usually ate one serve or less of fruit per day. Approximately one-fifth (18%) of Australians aged 18 years and over fell into both categories, eating almost no fruit or vegetables.

The proportion of the population with almost no fruit or vegetable intake generally decreased with age (graph 9.31). The highest rate was among 18-24 year olds, of whom 30% of males and 22% of females reported that they usually ate less than one serve each of fruit and vegetables per day.

Number of risk factors

In 1995 nearly half of all Australian adults did not smoke, took some exercise, and usually had at least one serve of fruit and/or vegetables per day (graph 9.32). More than a third (36%) had one of the risk factors, 13% had two risk factors, and 2% of all adults aged 18 years and over smoked, took no exercise, and ate almost no fruit or vegetables. About half of the adult population had none of the three risk factors, including 46% of males and 51% of females.

The proportion of people with all three risk factors varied between 4.6% of 35-44 year old males and 0.5% of 55-64 year old females, while the proportion with none of these risk factors ranged from 40% of 18-24 year old males to 58% of 55-64 year old females.

In virtually all age groups, men are more likely than women to exhibit all three risk factors, although the relationship with age is similar for both males and females.

Combination of risk factors

About half the people who smoked also had other risk factors, with 12% of smokers, or 2% of the adult population, also having no physical exercise, and almost no fruit or vegetable intake (table 9.33).

About three-fifths (61%) of people who took no physical activity had neither of the other risk factors. This was true for 44% of people who ate almost no fruit or vegetables, and 47% of people who smoked.

While only 2% of the adult population had all three risk factors, this is more than twice the proportion that could be expected if there were no correlation between these risk factors (if there were no correlation between the three risk factors, then 1.1% of Australians (21% of 18% of 30%) would be in this group).